<template>
    <div class="spec-preview">
        <img :src="imgObj.imgUrl"/>
        <div class="event" @mousemove="handler"></div>
        <div class="big">
            <img :src="imgObj.imgUrl" ref="big"/>
        </div>
        <div class="mask" ref="mask"></div>
    </div>
</template>

<script>
export default {
    name: "ZoomPage",
    props:['skuImageList'],
    data(){
      return{
          currentIndex:0
      }
    },
    computed:{
        imgObj(){
            return this.skuImageList[this.currentIndex]||{};
        }
    },
    mounted() {
        // 全局事件总线：获取兄弟组件的传递过来的索引值
       this.$bus.$on("getIndex",(index)=>{
           //修改当前的响应式的数据
            this.currentIndex=index;
       })
    },
    methods:{
        handler(event){
            let mask=this.$refs.mask;
            let big=this.$refs.big;
            let left=event.offsetX-mask.offsetWidth/2;
            let top=event.offsetY-mask.offsetHeight/2;
            //约束范围
            if (left<=0){
                left=0;
            }
            if (left>=mask.offsetWidth){
                left=mask.offsetWidth;
            }
            if (top<=0){
                top=0;
            }
            if (top>=mask.offsetHeight){
                top=mask.offsetHeight;
            }
            // 修改元素的left和top的属性值
            mask.style.left=left+'px';
            mask.style.top=top+'px';
            big.style.left = -2 * left + 'px';
            big.style.top = -2 * top + 'px';
        }
    }
}
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(255, 242, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>